Robotic arm-assisted total knee arthroplasty is associated with improved surgical and postoperative outcomes compared with imageless computer navigation

Aims: Computer-assisted technology has greater surgical accuracy for total knee arthroplasty (TKA); however, it is unclear if this is associated with better patient outcomes. There is a paucity of data comparing robotic arm-assisted TKA (RA-TKA) and computer-navigated TKA (nav-TKA). The aim of this study was to compare mid-term outcomes of image-based semiactive RA-TKA with imageless nav-TKA in a large patient cohort. Methods: Patient characteristics, surgical variables, complications, and patient-reported outcomes were recorded for 1,434 primary TKAs (388 RA-TKAs; 1,046 nav-TKAs) performed between November 2019 and October 2023 at a large tertiary hospital. Data were analyzed using Fisher's exact or Mann-Whitney U tests. Analyses were performed for cohorts matched for baseline demographics and follow-up time. Results: Compared to nav-TKA, matched RA-TKA cases had a shorter operating time (86.8 mins (SD 18.5) vs 93.3 mins (SD 23.6); p < 0.001), shorter length of stay (3.1 days (SD 1.4) vs 3.4 days (SD 1.6); p < 0.001), and fewer manipulations under anaesthesia (15 (4%) vs 29 (8%); p = 0.042). There were similar frequencies of inpatient complications (15 (4%) vs 22 (6%); p = 0.312), emergency department (ED) presentations (32 (8%) vs 41 (11%); p = 0.325), and revisions (five (1%) vs two (0.5%); p = 0.451) for RA-TKA and nav-TKA, respectively. At two years, RA-TKA patients reported higher Oxford Knee Score (41.2 (SD 6.7) vs 39.3 (SD 7.7); p = 0.003), EuroQol five-dimension questionnaire index (EQ-5D) (0.88 (SD 0.16) vs 0.82 (SD 0.20); p = 0.010), and EQ-5D Health (80.6 (SD 15.5) vs 77.2 (SD 16.9); p = 0.035), and lower levels of pain (11.0 (SD 18.2) vs 15.3 (SD 20.9); p < 0.001). Fewer RA-TKA patients were dissatisfied at six months (3% vs 7%; p = 0.034) and two years (3% vs 9%; p = 0.019). Conclusion: The findings suggest that image-based semiactive robotic assistance for TKA has benefits over imageless computer-assisted navigation, including shorter hospital length of stay, fewer MUAs, and improved mid-term patient-reported outcomes, but similar complications and ED presentations. Cost analysis showed that RA-TKA can have cost benefits at high-volume centres, however this needs to be weighed against the high initial cost of RA-TKA systems.